Use vendored template compiler.

Recent changes to Ember 1.2.0-beta.3 broke compatiblity with templates
compiled with prior versions of the `ember-template-compiler`.

This change allows us to use the version bundled in Bower with ember
itself.

Additional Notes:

* `grunt-ember-templates` added support for using custom
  templateCompilerPath/handlebarsPath in v0.4.17 (see [here](https://github.com/dgeb/grunt-ember-templates/pull/53)).
* The Ember package in bower is now publishing the template compiler
  (see
  [here](https://github.com/components/ember/commit/a1fc1f0f77d6cbeb854c9ba5ad328977e3e08d90)).
* A PR has been submitted to Ember (see
  [here](https://github.com/emberjs/ember.js/pull/3776)) to publish the
  template compiler along with release/beta/canary builds.
Merge pull request #313 from rjackson/use_correct_compiler_versions

Use vendored template compiler.
Merge remote-tracking branch 'upstream/master'